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This invention is directed to a low tire pressure indicator which is of simple and efficient construction and which can readily be installed on the valve stems of vehicle tires to provide a highly visible indication of tire pressure lower than a predetermined limit.
Proper maintenance of tire pressure is essential for optimizing the operation of a vehicle, as underinflation is the leading cause of tire failure. By maintaining the proper tire inflation, the life of the tire will be increased, the gas mileage of the vehicle will be improved, and the safety of the vehicle will be enhanced.
Tire failure is generally caused by overheating which typically results from one or a combination of tire defects, underinflation, or overloading. Tire heating is caused by the normal bending motion, or flex, in the sidewalls of a tire that occurs as a vehicle bounces up and down or moves side to side in turns. If the tires are properly inflated, the sidewalls will be stiff and the amount of flex will be minimized. However, if the tires are underinflated, they will become less stiff and the amount of flex will increase. Thereby, the tires will become more susceptible to overheating and failure.
The need for proper tire inflation has created a long time demand for various tire pressure devices. For instance, hand-held tire pressure gauges are well known and widely used. The user typically slides such a pressure gauge over the valve stem of the tire until the gauge sufficiently fits over the valve stem to create a seal that minimizes pressure escape between the tire and the gauge. Once the gauge has been appropriately positioned, the user notes the pressure value displayed on the gauge. The user then compares this value to the pressure value recommended by the manufacturer of the tire. The user must either refer to a manual or other source for this information or commit this value to memory.
Presently, all of the known tire pressure gauges either require a great deal of user intervention or do not provide a constant and instantaneous indication of whether the tire pressure has a value that is below a safe threshold limit. Most people seldom check tire pressure due to the inconvenience of these known gauges. Therefore, people fail to take an important role in preventing premature tire failure.
The present invention is directed towards providing a tire pressure indication device that continuously monitors the tire pressure and instantaneously generates a visual display having an easy to read indication as soon as the tire pressure falls below a safe threshold limit. The device of the present invention includes a dome shaped upper end. A two color dome shaped indicator element is disposed therein having two colors or other visually distinguishable markings which are visible through viewing areas. The dome element is rotatable in response to sensed tire pressure to provide a visual indication of low pressure and a visually distinct indication of safe pressure. A low pressure indication is provided, for example, by having a visible color distinct from the color of the dome cover present in the viewing area while one continuous color is displayed when a safe pressure is sensed. The lower end of the body includes a fitting to be fitted or threaded onto the valve stem of a tire.
The tire pressure causes displacement of a piston within the indicator body, which cooperates with a camming mechanism, to cause rotation of the indicator dome for displaying first and second visual indicator markings. The indicator is calibrated such that the dome element rotates sufficiently to provide the visual indication of low pressure in the viewing areas when the pressure falls below the threshold limit. Pressure which is lower than normal but not as low as the threshold limit provides less rotation of the indicator dome and therefore displays decreased but not completely low pressure.
The device includes multiple seals to substantially eliminate air from escaping to the atmosphere. Thereby, the device may be left on the tire valve and monitor tire pressure for long periods of time. Furthermore, the rotational movement of the indicator dome can be provided in a non-linear manner by appropriate design of cammed surfaces on top of the piston such that the indicator dome quickly rotates to a warning position when the pressure is sufficiently low.